Pressure sprayers of the relatively small, portable type have long been in use for spraying fruit trees, spraying insecticide in interiors (around baseboards, for example), spraying germicides for disinfecting hospital rooms and the like. These spraying devices have been of the manual, pneumatic type in which a hand-pump, incorporated in the structure is manually reciprocated, at the start of a spraying run, to build up an air pressure above the liquid in the tank sufficient to force liquid from the tank and through the spray nozzle. A difficulty with this mode of operation, aside from the inconvenience and tiring effect of the necessary manual working of the pump at the start of each spray session is that the pressure falls off as spraying proceeds varying the discharge and the operator has only very poor control over how much material, such as insecticide is deposited during the spraying operation.
The spraying apparatus of the present invention utilizes a pump, operated by a battery powered motor controlled by a pressure switch to provide a constant spraying pressure, giving a constant discharge and providing the operator with excellent control of the quantity of material deposited by the spraying operation. The spray nozzle is conventionally provided with a manually operated valve which is used for intermittant spraying. When the manual, spray-control valve is off, the pressure switch, because of the resulting rise in pressure in the discharge line, immediately deenergizes the pump motor. Battery energy is thus saved and there is no necessity for an electrical connection to the spray wand or spray valve. Manually opening the spray control valve lowers the pressure in the discharge line and the pump motor immediately restarts. With the motor switch remaining closed, control of the pump motor is thus accomplished without electric wiring into the liquid carrying spray wand or valve, thus avoiding obvious electrical hazard.